Cellulose derivative products



Patented Mar. 16, 1937 UNITED STATES OELLULOSE DERIVATIVE PRODUCTS Henry Dreyfus, London, England No Drawing. Application February 8, 1933, Serial No. 655,777. In Great Britain February 19,

8 Claims.

This invention relates to improvements in cellulose derivative products, and is more particularly directed to obtaining sheets, films and the like having improved water-proof properties.

Recently considerable attention has been directed to the use of cellulose acetate for the purpose of making thin sheets or foils for wrapping purposes. Cellulose acetate has very considerable advantages for this purpose as compared 10 with the well known cellulosic type of wrapping paper in that it is relatively resistant to water and can therefore be employed in wrapping articles which are wet or moist without risk of the package becoming seriously damaged, and also in sealing or partially sealing'the edges of the package it is unnecessary to employ a special adhesive, since the cellulose acetate sheets or edges can be united under heat and pressure or with the aid of solvents with or without pressure and/or heat.

o However, for certain purposes even cellulose acetate has not the high waterproofing properties which are desired, and it has been suggested that the cellulose acetate film or sheet shall be coated with a varnish of nitrocellulose'to improve its properties in this respect. The present invention also aims to increase the waterproofing properties of cellulose acetate.

I have now found that films, foils, sheets and the like containing or coated with cellulose esters containing radicles of higher fatty acids have improved waterproof properties. The products may contain a single cellulose ester in which part of, the acid radicles are derived from' acetic or other lower fatty acids and part from higher fatty acids, but preferably two or more cellulose esters or mixed esters are present. Particularly valuable are products comprising a simple ester of a lower fatty acid, e. g. cellulose acetate, and a simple ester of a higher fatty acid, preferably 40 higher saturated fatty acid.

Further, it is possible in accordance with the present invention to prepare as heretofore a foil or sheet of cellulose acetate or other cellulose derivative and to coat it either on one or both sides with the cellulose ester of the higher fatty acid. but I find that it is particularly advantageous to have the cellulose ester of the higher fatty acid uniformly disseminated throughout the material of cellulose acetate or other lower fatty acid ester of cellulose.

The lower fatty acid estersof cellulose to be used for the manufacture of sheets or foils may be cellulose acetates, formates, propionates, butyrates, or the like, and the higher fatty acid esters i may be cellulose laiu'ate, cellulose oleate, although as previously stated it is preferable to employ saturated esters, cellulose stearate and cellulose palmitate. The proportion of the esters to be mixed together for the manufacture of the sheets or foils or the proportion of the different ester 5 radicles in the mixed esters of cellulose may be varied within wide limits, In general I prefer to employ very considerable proportions of cellulose acetate or of acetyl radicles and to have comparatively limited proportions, such as up to 10 5, 10 or 15% of the higher fatty acid esters or the higher fatty acid radicles. As mentioned above, mixtures of mixed cellulose esters, e. g. cellulose aceto-propionate, cellulose nitro-acetate, cellulose aceto-stearate and cellulose aceto-palmitate, 15 may also be employed in the production of the films and the like according to the present invention.

The mixed esters may be prepared for use in the present invention by any suitable method. 20 For example the higher fatty acid radicles may be introduced into a cellulose already esterlfied with the lower fatty acid radicles, or alternatively a cellulose containing the desired proportion of stearic or other higher fatty acid radicles may 25 be treated so as to introduce acetyl, proplonyl or butyryl groups. Further the two types of ester radicle may be introduced simultaneously, as for example by treatment of the cellulose simultaneously with a mixture of the acid chlorides or 3;, acid anhydrides or by bringing about the introduction of the two radicles together in any other desired manner, as for instance by treatment of the cellulose with a mixture of the acids together with chloracetic anhydride. v

Whether a mixed ester or mixture of esters or mixed esters be employed in accordance with the present invention, it is of advantage to use a. body of as high an ester content as is consistent with solubility in the commercially available solvents. 40 The cellulose esters of lower fatty acids are, for instance, preferably di-esters or higher esters and .in the case of cellulose acetate it is possible to use an ester containing up to 2% ester groups or up to about 58 to 58.5% acetyl value and still retain 45 solubility in acetone or methyl ethyl ketone. To obtain the best results, it is not essential that the higher fatty acid esters should have quite such a high ester content as this, but here again, it is desirable to employ esters containing two or 0 somewhat more than two ester groups on the CcHmOs formula for cellulose. The total ester content of mixed esters is also advantageously between 2 and 3 and preferably about 2 ester groupsper cellulose molecule.

Pbrformingthesheetafoilsorthelikethe mixedestersorthemixturesofestersorofmixed esters may be dissolved in any suitable solvents. Among suitable solvents for the lower fatty acid esters of cellulose may be mentioned acetone, dioxane and methylene ethylene oxide and their alkyl or other substitution derivatives, mixtures of methylene or ethylene chloride and methyl or ethyl alcohol, while for the 8 fatty acid esters, benzene, toluene and other aromatic hydrocarbons are in general very suitable. Mixtures of esters may, for example, be dissolved in a mixture of liquids which are very good solvents for the individual esters as, for example, a mixture of acetone and benzene or its homologues inthecaseofusingamixtureofcelluloseacetate with cellulose laurate, stearate or palniitate. The solutions may also contain relatively high boiling solvents, e. g., diacetone alcohol, acetyl carbinol, acetyl acetone, cyclopentanone', cyclobutanone, the ethers, esters, and ether-esters of olefine glycols, of polyolefine glycols, and of other polyhydric alcohols, for instance the monomethyl ethers of ethylene glycol, ethyl lactate or mixtures of these solvents.

' The films and the like produced according to the present invention may also contain plasticizers, for example, sulphonamides, sulphonanilides or other sulphonarylides, alkyl phthalates, e. g. diethyl, dibutyl or diamyl phthalates, organic phosphates, for instance, tricresyi and triphenyl phosphate (preferably used in conjunction with sulphonamides or other plasticizers which are freely compatible with the cellulose derivatives), dimethyl, diethyl and dibutyl tartrates, mono-, 'di-' and tri-acetin, or mixtures of such substances. The plasticizer may be employed in any desired proportion depending p n the hardness and flexibility of the product required. For example, proportions oi up to 30% or more of plasticizer calculated on the total weight of-the cellulose derivative may be employed. Where it is desired to produce films or sheets of relatively low bility or which are substantially non-inflammable suitable agents for reducing the infiammability may also be incorporated in the composition. Such agents may be inorganic compounds e. g. phosphates and the like, but I prefer to employ agents which are compatible with the cellulose derivatives, for example, halogenated and preferably highly halogenated manic compounds. For this p rp se I may instance the hrominated derivatives of acidylated aromatic amines of U. 8. application S No. 386,100 filed May th1i929, for example diacetyl 2-4-6-tribromanilide. Such halogenated organic compounds may themselves act as plasticizing agents and in fact may be the sole plasticizing agent 00 present, though I prefer to employ them in con- Junction with sulphonamide or like plasticizers. In order to eliminate any powbility of deleterious action upon the sheets, films, etc. due to the presence oi free halogen or the liberation of halogen, small quantities of dicyandiamide or other agents capable of combining readily with halogen may be incorporated together with the agents torreducing flammability. With the brominated acidylated aromatic amines previously referred to such a precaution is not however a in general.

whereitisdesiredtoproduce mqueortranslucent films, suitable filling materials may be added to the compositions, e. g. mineral fillers such as zinc oxide. The invention particularly contemplates the production of transparent sheets or films however and it is preferred there- .fore only to add such substances as are soluble in or compatible with the cellulose derivatives. For the production of coloured films, sheets or the like any suitable pigments or dyestuffs may be incorporated with the compositions, and again for the production of water white sheets or films a suitable blue or blue-violet dyestufi or P 8- The compositions for use in the present processes may further contain any other suitable constituents for conferring upon the products any desired properties, for instance natural or synthetic resins, for increasing toughness and reducing brittleness, and affect materials in general. Suitable synthetic resins are those of the phenol-aldehyde, diphenyl-propane-aldehyde or -ketone, urea-aldehyde, toluene sulphonamide-aldehyde, and the glycerol-phthalic acid types, and also those obtainable by the polymerization of vinyl compounds, e. g. polymerized vinyl acetate. Constituents which are to be retained in the products are preferably so chosen as not materially to decrease "the water-resistant properties.

I The films, foils or sheetsmay be prepared by any suitable method. Preferably dry spinning processes are employed, in which solutions containing the cellulose derivatives are flowed or extruded through shaped orifices-or between rollers on to film-casting, wheels, bands or other smooth surfaces, or are received on rollers or the like. The use of wet-spinning processes is not however excluded. Again the films, foils and the like may be prepared by cutting from blocks.

The foils, films or sheets may be polished, or given any other desired finish either continuously with their production or after their formation. Where the foil is to be employed as a wrapping material it may be desirable that some design be printed or embossed upon it, and such processes may also be carried out continuously with the production of the foil. The embossing treatment is preferably applied to the foil whilst it is in a softened condition. Thus, the foil may be produced by extrusion between rollers, one or both of the surfaces of which are engraved in relief or intaglio to obtain the required embasal!!! effect.

The -following examples illustrate the produc-" tion of sheets, films and the like according to the present invention, but these examples are not to be considered as limiting the invention in Example 1 on to a suitable smooth metallic or glass surface,

e. g. of a film wheel, band or table. On evaporation of the solvent a film of cellulose derivative is obtained which may be removed from the casting surface and employed for any desired pur- Ecample 2 95-90 parts of cellulose acetate' and 5-10 parts of cellulose palmitate, 10 parts of diacetone alcohol and 5parts of dibutyl-phthalate, are dissum... 110.: 2,075,687

solved in a mixture of acetone and benzene. After filtration the solution is cast or flowed on to a suitable surface and the solvent evaporated. A film of cellulose derivative is produced which, after removal from the casting surface, may, if desired, be submitted to a seasoning treatment.

samples" Emmple 4 A 12-15% acetone solution of a cellulose acetostearate containing about 2-234 acetyl groups and V 45 stearyl group per CcHmOs unit is fiowed ontoafilmcesting whe'eltoformafilmhaving a thickness of about .001", which has improved waterproof properties.

- If desired, a suitable plasticizer, e. g. 10-30% of tricresylpr triphenyl phosphate, calculated on the weight ofthe cellulose derivative, may be incorporated in the solution.

Whilst the invention, as already stated, is of the greatest value in relation to the manufacture of sheets or foils, and particularly sheets or foils for wrapping purposes, it may also be applied to the manufacture of other products. Thus, the mixtures of esters of the present invention may be used for the manufacture of artificial silk either by dry or wet spinning processes. Again, the sheets or foils of the present invention are of considerable value in the manufacture of laminated glass, the cellulose derivative sheets 40 of the present invention having a very high ree' sistance to attack by moisture. The compositions mayalso be employed for waterproofing fabrics and other materials and in general for any purpose wherein a waterproofing coating is desired.

The term "base material" employed in the claims denotes the mixture of substances which forms the foundation or body of the composition or artificial product claimed, and does not 50 denote an agent that may be added to modify the properties of these substances, such as a f espritons plasticiser, a solvent or an effect material, or to act merely as a filler.

The term lower fatty acid, as employed in the claims, denotes a fatty acid containing atmost 4 carbon atoms in the molecule and the term higher fatty acid" denotes a fatty acid containing at least 12 carbon atoms in the molecule.

What I claim and desire to secure by Letters Patent is:-

1. Liquid and solid compositions of matter in which the base material consists of cellulose esters of lower fatty acids only and a relatively small proportion of cellulose esters of higher fatty acids only.

2. Films, foils, sheets, filaments and like articles in which the base material consists of cellulose esters of lower fatty acids only and a relatively small proportion of cellulose esters of higher fatty acids only.

- 3. Films, foils, sheets and the like in which the base material consists of between 85 and 95% of cellulose esters of lower fatty acids only and between 5 and 15% of cellulose esters of higher fatty acids only.

4. Films, foils, sheets, filaments, and like. articles in which the base material consists of between 85 and 95% of cellulose-acetate and between 5 and 15% of cellulose esters of higher fatty acids only.

5. Films, foils, sheets and the like in which the base material consists of between 85 and 95% of cellulose acetate and between 5 and 15% of a simple cellulose ester of a saturated higher fatty acid.

6. Films, foils, sheets and the like in which the base material consists of between 85 and 95% of cellulose acetate and between 5 and 15% of a simple cellulose ester of a saturated higher fatty acid, eachcellulose ester employed having an ester content of at least two ester groups per CsHmOs unit.

7. Films, foils, sheets and the like in which the base material consists of between and of cellulose acetate and between 5 and 15% of cellulose stearate.

8. Films, foils, sheets and the like in which the base material consists of between 85 and 95% of cellulose acetate and between 5 and 15% of cellulose palmitate.

- HENRY DREYFUB.

cossscrros.

March 16, 1937'.

1mm oRsrrus- It is hereby certified that error appears in the printed specification of the above numbered patent requiring. correction as follows: second column, line 21. for the word '"affect" read effect; and that the said Letters Patent should be read with this correction therein that that: same may conform to the record of the case in the Patent Office. I

Signed and sealed this 6th day of April, A. D. 1937.

Page 2,

Henry Van Arsdale Acting Commissioner of Patents.

sum... 110.: 2,075,687

solved in a mixture of acetone and benzene. After filtration the solution is cast or flowed on to a suitable surface and the solvent evaporated. A film of cellulose derivative is produced which, after removal from the casting surface, may, if desired, be submitted to a seasoning treatment.

samples" Emmple 4 A 12-15% acetone solution of a cellulose acetostearate containing about 2-234 acetyl groups and V 45 stearyl group per CcHmOs unit is fiowed ontoafilmcesting whe'eltoformafilmhaving a thickness of about .001", which has improved waterproof properties.

- If desired, a suitable plasticizer, e. g. 10-30% of tricresylpr triphenyl phosphate, calculated on the weight ofthe cellulose derivative, may be incorporated in the solution.

Whilst the invention, as already stated, is of the greatest value in relation to the manufacture of sheets or foils, and particularly sheets or foils for wrapping purposes, it may also be applied to the manufacture of other products. Thus, the mixtures of esters of the present invention may be used for the manufacture of artificial silk either by dry or wet spinning processes. Again, the sheets or foils of the present invention are of considerable value in the manufacture of laminated glass, the cellulose derivative sheets 40 of the present invention having a very high ree' sistance to attack by moisture. The compositions mayalso be employed for waterproofing fabrics and other materials and in general for any purpose wherein a waterproofing coating is desired.

The term "base material" employed in the claims denotes the mixture of substances which forms the foundation or body of the composition or artificial product claimed, and does not 50 denote an agent that may be added to modify the properties of these substances, such as a f espritons plasticiser, a solvent or an effect material, or to act merely as a filler.

The term lower fatty acid, as employed in the claims, denotes a fatty acid containing atmost 4 carbon atoms in the molecule and the term higher fatty acid" denotes a fatty acid containing at least 12 carbon atoms in the molecule.

What I claim and desire to secure by Letters Patent is:-

1. Liquid and solid compositions of matter in which the base material consists of cellulose esters of lower fatty acids only and a relatively small proportion of cellulose esters of higher fatty acids only.

2. Films, foils, sheets, filaments and like articles in which the base material consists of cellulose esters of lower fatty acids only and a relatively small proportion of cellulose esters of higher fatty acids only.

- 3. Films, foils, sheets and the like in which the base material consists of between 85 and 95% of cellulose esters of lower fatty acids only and between 5 and 15% of cellulose esters of higher fatty acids only.

4. Films, foils, sheets, filaments, and like. articles in which the base material consists of between 85 and 95% of cellulose-acetate and between 5 and 15% of cellulose esters of higher fatty acids only.

5. Films, foils, sheets and the like in which the base material consists of between 85 and 95% of cellulose acetate and between 5 and 15% of a simple cellulose ester of a saturated higher fatty acid.

6. Films, foils, sheets and the like in which the base material consists of between 85 and 95% of cellulose acetate and between 5 and 15% of a simple cellulose ester of a saturated higher fatty acid, eachcellulose ester employed having an ester content of at least two ester groups per CsHmOs unit.

7. Films, foils, sheets and the like in which the base material consists of between and of cellulose acetate and between 5 and 15% of cellulose stearate.

8. Films, foils, sheets and the like in which the base material consists of between 85 and 95% of cellulose acetate and between 5 and 15% of cellulose palmitate.

- HENRY DREYFUB.

cossscrros.

March 16, 1937'.

1mm oRsrrus- It is hereby certified that error appears in the printed specification of the above numbered patent requiring. correction as follows: second column, line 21. for the word '"affect" read effect; and that the said Letters Patent should be read with this correction therein that that: same may conform to the record of the case in the Patent Office. I

Signed and sealed this 6th day of April, A. D. 1937.

Page 2,

Henry Van Arsdale Acting Commissioner of Patents. 

